Intersomatic cage with unified grafts

Abstract

An intervertebral cage includes a thin main wall having two return parts at opposite ends of the wall. The wall has an approximately constant thickness. The return parts are extended by facing end parts having a gap between them. The wall, the return parts and end parts delimit an inner cavity. The gap extends parallel to the wall and has a length between 50% and 100% of the cavity length. The gap length is preferably between 70% to 90% of the cavity length.

The invention claimed is: 
     
       1. An intervertebral cage configured for insertion between an upper vertebra and a lower vertebra, comprising:
 an elongated main wall having first and second opposing ends thereof; 
 a first return part extending away from the first end of the main wall; 
 a second return part extending away from the second end of the main wall; 
 a first end part extending from the first return part and terminating at a first end face; 
 a second end part extending from the second return part and terminating at a second end face; 
 an upper surface configured for contact with the upper vertebra, the upper surface comprising teeth arranged in a substantially planar array and at least portions of the main wall, the first return part, the second return part, the first end part, and the second end part; 
 a lower surface configured for contact with the lower vertebra, the lower surface comprising teeth arranged in a substantially planar array and at least portions of the main wall, the first return part, the second return part, the first end part, and the second end part; and 
 a cavity delimited by the main wall, the first return part, the second return part, the first end part, and the second end part, the cavity open along the upper surface and the lower surface, with the intervertebral cage having an opening to the cavity along a gap; 
 the gap formed between the first end face and the second end face and having a width that corresponds to between 100% and about 50% of the largest dimension of the cavity parallel to the main wall, which width extends fully along the opening between the first end face and the second end face, with the gap open at the upper surface and the lower surface and extending therebetween so that the first end part and the second end part are connected only through the first return part, the second return part, and the main wall; and 
 a coupler for a placement instrument disposed in the first or second return part or the first or second end part and adapted to place the cage between the upper and lower vertebrae. 
 
     
     
       2. The intervertebral cage of  claim 1  in which the main wall is substantially straight. 
     
     
       3. The intervertebral cage of  claim 2  in which the main wall has a thickness defined by the distance between an exterior wall extending from the upper surface to the lower surface and an interior wall extending from the upper surface to the lower surface, the thickness being substantially constant between the upper surface and the lower surfaces. 
     
     
       4. The intervertebral cage of  claim 3  in which the main wall and the first and second end parts have substantially the same thickness. 
     
     
       5. The intervertebral cage of  claim 1  in which the first end face and the second end face are substantially flat and substantially parallel. 
     
     
       6. The intervertebral cage of  claim 1  wherein the gap extends substantially parallel to the main wall. 
     
     
       7. The intervertebral cage of  claim 1  wherein the gap extends substantially parallel to the main wall and corresponds to between about 90% and about 70% of the largest dimension of the cavity parallel to the main wall. 
     
     
       8. The intervertebral cage of  claim 1  further comprising a longitudinal bevel adapted to restore a lordosis. 
     
     
       9. The intervertebral cage of  claim 1  in which the teeth of the upper surface and the lower each extend along the main wall, the first return part, the second return part, the first end part, and the second end part. 
     
     
       10. A combination comprising the intervertebral cage of  claim 1  and further comprising a placement instrument for inserting the cage between the upper and lower vertebrae, the coupler of the intervertebral cage further comprising an attachment for a rod of the instrument, and the instrument comprising a rod attachable to the coupler and an instrument wall adapted to extend at least partially into the gap and to close the gap between the first and second end faces. 
     
     
       11. The intervertebral cage and instrument of  claim 10  wherein the instrument wall is offset from a center line of the rod. 
     
     
       12. The intervertebral cage and instrument of  claim 10  further comprising a blocking structure adapted to block rotation of the cage. 
     
     
       13. The intervertebral cage and instrument of  claim 10  wherein the coupler includes a hole disposed in the cage adapted to receive a portion of the rod. 
     
     
       14. The intervertebral cage and instrument of  claim 13  further comprising a blocking structure integral with the coupler, wherein the hole disposed in the cage is tapped and the portion of the rod received in the hole is threaded. 
     
     
       15. An intervertebral cage configured for insertion between an upper vertebra and a lower vertebra, comprising:
 a substantially straight main wall comprising a top adapted for contact with the upper vertebra and a bottom adapted for contact with the lower vertebra, and having first and second ends each extending from the top to the bottom of the main wall; 
 a first return part extending away from the first end of the main wall, the first return part having a top adapted for contact with the upper vertebra, a bottom adapted for contact with the lower vertebra, and a first end part having a top adapted for contact with the upper vertebra and a bottom adapted for contact with the lower vertebra; 
 a second return part extending away from the second end of the main wall, the second return part having a top adapted for contact with the upper vertebra, a bottom adapted for contact with the lower vertebra, and a second end part having a top adapted for contact with the upper vertebra and a bottom adapted for contact with the lower vertebra, the first end part extending from the first return part toward the second end part and the second end part extending from the second return part toward the first end part so that the first and second end parts face each other to form a gap therebetween; 
 a cavity defined by the main wall, the first and second return parts and the first and second end parts that opens from the cage at the gap, the gap extending substantially parallel to the main wall a distance that is between 100% and about 50% of a largest dimension of the cavity parallel to the wall; and 
 a coupler for a placement instrument disposed in the first or second return part or the first or second end part and adapted to place the cage between the upper and lower vertebrae; 
 with the main wall having a thickness defined by the distance between an exterior surface extending from the top to the bottom of the main wall and an interior surface extending from the top to the bottom of the main wall, the thickness being substantially constant between the top and the bottom of the main wall. 
 
     
     
       16. An intervertebral cage configured for insertion in a space between an upper vertebra and a lower vertebra, the intervertebral space having a medial horizontal plane, the cage comprising:
 a substantially straight main wall having two ends; 
 first and second return parts each projecting from one of the two main wall ends; 
 a first end part extending toward the second return part from an end of the first return part distal from the main wall; 
 a second end part extending toward the first return part from an end of the second return part distal from the main wall; 
 a gap between the first and second end parts; 
 an inner cavity defined by the main wall, the first and second return parts, the first and second end parts, and the gap, with the gap extending substantially parallel to the main wall along a distance between 100% and about 50% of the largest dimension of the inner cavity parallel to the main wall; 
 a top surface comprising notches arranged in a substantially planar array and adapted to confront the upper vertebra; 
 a bottom surface comprising notches arranged in a substantially planar array and adapted to confront the lower vertebra; 
 a cross-sectional shape along the top and the bottom surfaces of the cage that approximates the shape of a letter “C” having a substantially straight back; and 
 a coupler for a placement instrument disposed in the first or second return part or the first or second end part and adapted to place the cage between the upper and lower vertebrae. 
 
     
     
       17. The intervertebral cage of  claim 16  in which the cage has a lateral width and at least one of the notches of the top and bottom surfaces extends across the lateral width. 
     
     
       18. An intervertebral cage combination comprising a first intervertebral cage according to  claim 16  and a second intervertebral cage according to  claim 16 , wherein the first intervertebral cage and the second intervertebral cage are configured with mirror-image symmetry and adapted for disposition with the gap of the first intervertebral cage facing the gap of the second intervertebral cage. 
     
     
       19. The intervertebral cage of  claim 16 , further comprising
 a first wall surface extending along a first side of the substantially straight main wall, a first side of the first return part, and a first side of the second return part and 
 a second wall surface extending along a second side of the substantially straight main wall, a second side of the first return part, and a second side of the second return part; 
 with the top surface and the bottom surface each extending contiguously from the first wall surface to the second wall surface.